U.S. patent application number 16/334043 was filed with the patent office on 2019-09-05 for process for the modification of humins.
The applicant listed for this patent is Avantium Knowledge Centre B.V.. Invention is credited to Edserd De Jong, Alice Cristina Mija, Jan Cornelis van der Waal, Gerardus Petrus Maria van Klink.
Application Number | 20190270854 16/334043 |
Document ID | / |
Family ID | 57104164 |
Filed Date | 2019-09-05 |
United States Patent
Application |
20190270854 |
Kind Code |
A1 |
Mija; Alice Cristina ; et
al. |
September 5, 2019 |
PROCESS FOR THE MODIFICATION OF HUMINS
Abstract
Modified humins are prepared by contacting humins with a
reactive compound, such as, a carboxylic acid, an acyl halide, a
carboxylic anhydride, an olefin, an epoxy-group containing compound
and combinations thereof in the presence of an organic aprotic
solvent to obtain a humins-containing admixture; maintaining the
humins-containing admixture at elevated temperature to achieve a
reaction between the humins and the reactive compound, thereby
obtaining modified humins; and recovering the modified humins.
Inventors: |
Mija; Alice Cristina; (Nice,
FR) ; van der Waal; Jan Cornelis; (Amsterdam, NL)
; De Jong; Edserd; (Amsterdam, NL) ; van Klink;
Gerardus Petrus Maria; (Amsterdam, NL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Avantium Knowledge Centre B.V. |
Amsterdam |
|
NL |
|
|
Family ID: |
57104164 |
Appl. No.: |
16/334043 |
Filed: |
September 29, 2017 |
PCT Filed: |
September 29, 2017 |
PCT NO: |
PCT/NL2017/050651 |
371 Date: |
March 18, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01G 9/2027 20130101;
Y02E 10/542 20130101; C08L 97/00 20130101; C08L 63/00 20130101;
Y02E 60/13 20130101; C08H 6/00 20130101; C08L 63/00 20130101 |
International
Class: |
C08H 7/00 20060101
C08H007/00; H01G 9/20 20060101 H01G009/20 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 29, 2016 |
NL |
2017547 |
Claims
1. A process for the modification of humins comprising: contacting
humins with a reactive compound selected from the group consisting
of a carboxylic acid, an acyl halide, a carboxylic anhydride, an
olefin, an epoxy-group containing compound and combinations thereof
in the presence of an organic aprotic solvent to obtain a
humins-containing admixture; maintaining the humins-containing
admixture at elevated temperature to achieve a reaction between the
humins and the reactive compound, thereby obtaining modified
humins; and recovering the modified humins.
2. The process according to claim 1, wherein the reactive compound
is selected from the group consisting of a carboxylic acid with a
number of carbon atoms of 1 to 25, an acyl halide with a number of
carbon atoms of 1 to 25, a carboxylic anhydride with acyl groups
having a number of carbon atoms of 2 to 25, an olefin having a
number of carbon atoms of 4 to 20, an epoxy-group containing
compound selected from the group consisting of C.sub.1-C.sub.6
alkyl glycidyl ethers, bisphenol A diglycidyl ethers, glycidyl
esters of C.sub.1-C.sub.6 carboxylic acids, epoxidized vegetable
oils and combinations thereof.
3. The process according to claim 2, wherein the carboxylic
anhydride is selected from a C.sub.2-C.sub.6 carboxylic anhydride,
in particular from acetic anhydride and succinic anhydride.
4. The process according to claim 1, wherein the reactive compound
comprises an olefin having from 4 to 8 carbon atoms.
5. The process according to claim 4, wherein the olefin is selected
from the group consisting of butenes, pentenes, hexenes, heptenes,
octenes and combinations thereof.
6. The process according to claim 1, wherein the organic aprotic
solvent is selected from the group consisting of aldehydes,
ketones, carboxylic acid esters and combinations thereof.
7. The process according to claim 6, wherein the organic aprotic
solvent is selected from the group consisting of acetone, methyl
ethyl ketone, methyl iso-butyl ketone, gamma-valerolactone, ethyl
formate, propyl formate, methyl acetate, ethyl acetate, methyl
levulinate, ethyl levulinate, and combinations thereof.
8. The process according to claim 1, wherein the amount of organic
aprotic solvent is in the range of 1 to 50 mL, organic aprotic
solvent per gram humins.
9. The process according to claim 1, wherein the amount of reactive
compound per amount of humins is from 0.001 to 1.0 g reactive
compound per g humins.
10. The process according to claim 1, wherein the humins-containing
admixture is maintained at a temperature in the range of 50 to
250.degree. C.
11. The process according to claim 1, wherein the humins-containing
admixture is maintained at elevated temperature for a period in the
range of 0.2 to 6 h.
12. The process according to claim 1, wherein the modified humins
are washed with an aqueous washing liquid.
13. The process according to claim 12, wherein the modified humins
are taken up in a water-immiscible solvent and the solution
obtained is then subjected to liquid-liquid extraction with the
aqueous washing liquid.
14. Modified humins obtainable from the process according to claim
1.
15. Modified humins having a complex viscosity of at most 50 Pas,
preferably a complex viscosity in the range of 5 to 50 Pas,
measured at 60.degree. C. at a frequency of 10 Hz, determined in
accordance with ASTM D7175.
16. Modified humins, comprising furyl groups, which further
comprise acyl moieties derived from a reactive compound selected
from the group consisting of a carboxylic acid, an acyl halide and
a carboxylic anhydride.
17. Modified humins according to claim 16, wherein the acyl
moieties are the residues of carboxylic acids having a number of
carbon atoms in the range of 1 to 25 carbon atoms.
18. Modified humins according to claim 16, wherein the acyl
moieties are selected from formyl, acetyl, propionyl, butyryl
groups and combinations thereof.
19. Modified humins according to claim 16, wherein the acyl
moieties are residues of succinic acid.
20. Modified humins according to claim 19, which are solid and are
electrically conductive.
21. Modified humins comprising furyl groups, which further comprise
phenyl or oxa-[2,2,1]-bicyclo-heptenyl groups derived from an
olefin reactive compound.
22. Modified humins according to claim 21, wherein the olefin has
from 4 to 20 carbon atoms, preferably from 4 to 8 carbon atoms.
23. Modified humins, comprising furyl groups, which further
comprise ether moieties derived from a reactive compound selected
from epoxy-group containing compounds.
24. Modified humins according to claim 23, wherein the epoxy-group
containing compound has been selected from the group consisting of
C.sub.1-C.sub.6 alkyl glycidyl ethers, bisphenol A diglycidyl
ethers, glycidyl esters of C.sub.1-C.sub.6 carboxylic acids,
epoxidized vegetable oils and combinations thereof.
25. Utilizing the Use of modified humins according to claim 13 as
photosensitizer in dye-sensitized solar cells.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is the National Stage of International
Application No. PCT/NL2017/050651, filed Sep. 29, 2017, which
claims the benefit of Netherlands Application No. NL 2017547, filed
Sep. 29, 2016, the contents of which is incorporated by reference
herein.
FIELD OF THE INVENTION
[0002] The present invention relates to a process for the
modification of humins and to modified humins thus obtainable.
BACKGROUND OF THE INVENTION
[0003] Humins constitute a known material. U.S. Pat. No. 3,293,200
describes thermosetting adhesive compositions that are useful in
the manufacture of plywood and contain, as essential ingredients, a
water-soluble phenol-aldehyde resin and a water-insoluble,
finely-divided humins material obtained from the manufacture of
levulinic acid by acid hydrolysis of lignocellulose, i.e. a natural
product comprising a combination of carbohydrates and lignin.
Although various procedures are known for the manufacture of
levulinic acid from lignocellulose, the reaction generally is
carried out under severe acid hydrolysis conditions at a
temperature in excess of 150.degree. C., usually between
170.degree. C. and 210.degree. C. in the presence of a strong acid
catalyst. During the reaction, humins material is formed as a
result of an acid catalyzed breakdown of lignocellulose while
substantially the entire carbohydrate portion of the lignocellulose
is degraded to hexosans and the hexosans are converted to the
desired levulinic acid.
[0004] Humins have been obtained in the dehydration of
carbohydrates in the manufacture of levulinic acid,
5-hydroxymethylfurfural and/or 5-alkoxymethylfurfural and/or
acyloxymethyl-furfural. Humins are also formed in the conversion of
5-hydroxymethylfurfural to levulinic acid and formic acid (cf. G.
Tsilomelekis et al., Green Chem., 2016, 18, 1983-1993). An example
of such a dehydration reaction of carbohydrates is described in DE
3621517. Other examples of humins-producing processes are described
in WO 2007/104514 describing the preparation of
5-alkoxymethylfurfural, and WO 2007/104515, disclosing the
preparation of 5-acyloxymethylfurfural. Although the latter
processes have set out to reduce the yield of humins, the processes
unavoidably yield amounts of humins for which a useful outlet is
sought. The processes are typically conducted in the presence of an
acid catalyst. Catalysts used are generally mineral acids. In the
process of recovering the desired products, the catalyst used is
typically neutralized whereby salts are obtained. These salts are
recovered together with the humins.
[0005] A potential use of humins has been described in DE 3621517,
where it is stated that the humins, i.e. the by-product of the
preparation of alkoxymethylfurfural and alkyl levulinates from
cellulose, lignocellulose or starch with an alcohol, are filtered
from the liquid products and can only be used for the provision of
heat by combusting it. Also in WO 2010/124381 the conversion of
cellulose has been described, leading to glucose,
hydroxymethylfurfural and other small organic compounds on the one
hand and a humins-containing biofuel on the other hand. The biofuel
is obtained as a solid. The feature that the biofuel is solid
already hampers the application thereof. Moreover, the presence of
inorganic salts that result from the neutralization of acid
catalysts used, are also detrimental for the use of humins, even as
biofuel. It would therefore be very advantageous, if humins can be
used in a more economic and value-added application, e.g. as a
liquid fuel, and which may be obtained in a salt-free phase.
[0006] In WO 2015/088341 the use of humins in the preparation of
viscous resins has been described. A blend of humins and furfural
alcohol is mixed with an acidic polymerization initiator. The
resulting admixture may be cured at elevated temperature to result
in a viscous resin, which can be used for the preparation of an
adhesive. In a particular example furfuryl alcohol, humins and
maleic anhydride were mixed and allowed to react at a temperature
in the range of 105 to 145.degree. C. A viscous resin was obtained.
It appeared that at the reaction conditions furfuryl alcohol and
humins polymerized resulting in the viscosity increase.
SUMMARY OF THE INVENTION
[0007] It has now been found that a significant viscosity decrease
for humins can be obtained when the humins are modified with
certain reactive compounds. Accordingly, the present invention
provides a process for the modification of humins comprising:
[0008] contacting humins with a reactive compound selected from the
group consisting of a carboxylic acid, a carboxylic halide, a
carboxylic anhydride, an olefin, an epoxy-group containing compound
and combinations thereof in the presence of an organic aprotic
solvent to obtain a humins-containing admixture; [0009] maintaining
the humins-containing admixture at elevated temperature to achieve
a reaction between the humins and the reactive compound, thereby
obtaining modified humins; and [0010] recovering the modified
humins.
DETAILED DESCRIPTION OF THE INVENTION
[0011] Furfuryl alcohol is a protic solvent. It has the drawback of
being able to polymerize and thereby to increase the viscosity, and
is therefore not a suitable solvent.
[0012] In this specification humins are the colored bodies which
are carbonaceous water-insoluble by-products of the dehydration of
carbohydrates and/or 5-hydroxymethylfurfural and/or ethers or
esters of 5-hydroxymethylfurfural. They are believed to be polymers
containing moieties from 5-hydroxymethylfurfural, furfural,
residual carbohydrate and levulinic acid. These colored bodies are
inter alia produced as by-products in the partial degrading of
carbohydrates by heat or other processing conditions, as described
in e.g. EP 338151. The molecular structure of humins is not yet
unequivocally established. Humins are believed to be macromolecules
containing inter alia furfural and hydroxymethylfurfural moieties.
Further moieties that may be included in humins are carbohydrate,
levulinate and alkoxymethyl furfural groups. A mechanism for the
formation of humins molecules may be a polycondensation pathway,
leading to a network of furan rings linked by ether and acetal
bonds. A structure for humins is presented in I. van Zandvoort et
al. ChemSusChem, 2013, 6, 1745-1758. In this journal article the
humins structure is characterized by furan rings connected via
alkylene moieties. Thus, typical for humins are furan rings and
alkylene groups, such as methylene and ethylene groups, whereas
other constituent groups may be hydroxyl, aldehyde, ketone, ether,
carboxylic acid and ester groups. When the dehydration of the
carbohydrates into furan derivatives is carried out in the presence
of an organic solvent other functional groups, such as alkoxy and
alkyl ester groups, may be present.
[0013] Humins may also be characterized with reference to the Van
Krevelen diagram. In such a diagram the hydrogen index, i.e. the
atomic hydrogen:carbon ratio, and the oxygen index, i.e. the atomic
oxygen:carbon ratio, are plotted against each other. It was found
that humins suitably have an oxygen:carbon atomic ratio in the
range of 0.30 to 0.70, preferably from 0.40 to 0.60 and a
hydrogen:carbon atomic ratio in the range of 0.60 to 1.6,
preferably from 0.80 to 1.40. In this specification humins are in
particular water insoluble by-products that have been obtained from
the acid-catalyzed dehydration of carbohydrates, such as cellulose,
starch, sugars such as glucose, fructose and combinations thereof.
Such dehydration processes are suitably used for the conversion of
carbohydrates to levulinic acid or esters thereof, or
5-hydroxymethylfurfural or ethers or esters thereof. Such processes
have i.a. been described in the above-mentioned patent documents DE
3621517, WO 2007/104514 and WO 2007/104515. The humins are
generally water-insoluble. However, they tend to be very
hydrophilic. Their hydroxyl and carboxyl moieties give the humins a
hydrophilic character. When some of the polymeric components of the
humins are relatively small, they may be incorporated into water
when these components are contacted with an aqueous medium. The
hydrophilic behavior of humins may result in the formation of
colloids when humins are contacted with water. That may make it
difficult to wash humins with an aqueous medium. Since washing with
water is troublesome, the removal of inorganic salts by washing
with water tends to be hampered by the hydrophilicity of
humins.
[0014] Without wishing to be bound by any theory it is believed
that the reactive compounds that are used in the present process
react with functional groups in humins, thereby reducing the
hydrophilic character of the modified humins. The reduced
hydrophilic character of the modified humins provides a number of
advantageous properties. The modified humins have a lesser tendency
to combine with an aqueous medium. Therefore it is easier to purify
the modified humins by washing with water or an aqueous medium, in
order to remove inorganic material, such as salts. The presence of
salts may be detrimental to the heating value of the humins.
Moreover, some inorganic materials, such as sulfates, are
undesirable in any combustible fuel since noxious sulfur oxides may
be formed. By being able to remove sulfur-containing inorganic
material from humins, the skilled person can enhance the usefulness
of the modified humins as fuel. A further advantage is that the
modified humins tend to get a reduced viscosity. Therefore they can
be used, e.g. as liquid fuel. This represents a considerable
advantage over the known use of humins as solid fuel which is more
difficult to handle. Moreover, the modified humins tend to be
soluble in organic solvents and hydrocarbons. Therefore, the
modified humins can conveniently be blended with organic solvents
and/or fuels so that the modified humins can be used in
conventional liquid fuels, such as diesel or heavy gasoil or
residual oil.
[0015] The reactive compound that is used in the process according
to the present invention is selected from the group consisting of a
carboxylic acid, a carboxylic anhydride, a carboxylic halide, an
olefin, an epoxy-group containing compound and combinations
thereof. When the reactive compound is a carboxylic acid, the
carboxylic acid may be chosen from a wide range of carboxylic
acids. The number of carbon atoms may be in the range of 1 to 25
carbon atoms. Suitable acids include formic acid, acetic acid,
propionic acid, butyric acid, valeric acid, hexanoic acid, but also
lauric acid or stearic acid. The carboxylic acid may be saturated,
but also unsaturated. Suitable unsaturated carboxylic acids have 3
to 20 carbon atoms and may have one or more unsaturated bonds. A
suitable unsaturated acid is e.g. acrylic acid, linoleic acid,
linolenic acid or oleic acid. The carboxylic acid may comprise one
or more, e.g. from one to four carboxylic groups. Accordingly, the
process of the present invention can also be carried out with
diacids or triacids. Such acids may contain from 2 to 20 carbon
atoms and include e.g. oxalic acid, malonic acid, succinic acid,
adipic acid and sebacic acid. As indicated, the carboxylic acid may
be used as such. An example of an unsaturated diacid is maleic
acid. The carboxylic acid may also comprise other functional groups
and/or heteroatoms. Such functional groups may for instance be
selected from one or more of amino, aldehyde, hydroxyl, amido and
ether groups. Further, the carboxylic acids may comprise one or
more heteroatoms in the acyl moiety, such as oxygen or nitrogen
groups. When the modified humins are used in applications wherein
the modified humins are combusted the hetero atom is preferably
oxygen and the functional groups suitably comprise carbon, hydrogen
and/or oxygen, as nitrogen and other heteroatoms, such as sulfur
and phosphorus could result in noxious combustion gases. Examples
of such suitable carboxylic acids include lactic acid and levulinic
acid.
[0016] The reactive compound may also be selected from acyl
halides. The halogen moiety of the halide can be a fluoride,
chloride, bromide or iodide. In view of the costs, availability and
ease of handling, the use of the chloride is preferred. The acyl
moiety of the acyl halide may comprise a wide variety of carbon
atoms. Similarly to the carboxylic acids that are mentioned
hereinbefore, the carbonyl moiety in the acyl halides may have a
number of carbon atoms in the range of 1 to 25 carbon atoms,
Suitable examples include acetyl chloride, acetyl bromide,
propionyl chloride, butyryl chloride, but also longer chain
molecules such as lauroyl chloride or stearoyl chloride. The acyl
halides may also be derived from polyacids, such as di-, tri- or
tetra-acids. An example of such an acyl halide is sebacoyl
chloride.
[0017] When the reactive compound is selected from a carboxylic
anhydride, the carboxylic acids that may be used to compose the
anhydride can be selected from a wide range of acids. The acids may
have a number of carbon atoms in the range of 2 to 25 carbon atoms.
Suitable acids include acetic acid, propionic acid, butyric acid,
valeric acid, hexanoic acid, but also lauric acid or stearic acid.
The carboxylic acid may be saturated, but also unsaturated.
Suitable unsaturated carboxylic acids have 3 to 20 carbon atoms and
may have one or more unsaturated bonds. Preferably, the two
carboxylic acids that form the anhydride are the same. Therefore,
the acids having from 2 to 25 carbon atoms are suitably selected
from acetic anhydride, propionic anhydride, butyric anhydride,
valeric anhydride, and stearic anhydride. Anhydrides tend to react
quickly with the humins macromolecules. In the reaction one of the
carboxylic acid moieties from the anhydride is released and may
react further with a functional group of the humins macromolecule.
The acids forming the anhydride may also be selected from
polyacids, in particular from diacids. Preferably, the carboxylic
anhydride is selected from a diacid having from 4 to 6 carbon
atoms. In particular the preferred anhydride is succinic anhydride.
The carboxylic anhydride may also comprise unsaturated carboxylic
acid moieties. When the carboxylic acid that is used to form the
anhydride is unsaturated, a preferred carboxylic anhydride is
maleic anhydride.
[0018] When the reactive compound is a carboxylic acid, a
carboxylic anhydride, or an acyl halide, the chain that is attached
to the carboxyl or carbonyl group is preferably saturated. When the
reactive compound comprises an unsaturated carbon-carbon bond in
addition to the reactive carboxyl or carbonyl group, the reactive
compound may become too reactive so that the modified humins
obtained may be cross-linked and formed into an insoluble solid.
Therefore, the reactive compound selected from the group consisting
of a carboxylic acid, an acyl halide and a carboxylic anhydride, is
suitably a saturated compound.
[0019] The reactive compound may also be an olefin. The olefin
compound may have more than one unsaturated bond. However, it is
believed that the reaction that takes place is a type of Diels
Alder reaction, wherein a reactive diene is provided by the furan
rings of the humins and the added olefin provides the dienophile.
Therefore, the unsaturated compound suitably does not contain
conjugated double bonds. Preferably, the olefin is a mono-olefin.
The olefin may comprise heteroatoms, e.g. by means of an ether
linkage or an aldehyde or ketone moiety. Preferably, the olefin is
a hydrocarbyl compound, comprising only hydrogen and carbon. In
this way the hydrophobicity of the product is enhanced. The olefin
may have from 4 to 20 carbon atoms, preferably from 4 to 8 carbon
atoms. Preferably, the olefin is selected from the group consisting
of butenes, pentenes, hexenes, heptenes, octenes and combinations
thereof. Examples of suitable olefins include 1-butene, 2-butene,
1-hexene, 1,7-octadiene, and mixtures thereof.
[0020] The reactive compound may be selected from epoxy-group
containing compounds. Examples are compounds that comprise a
glycidyl group, such as C.sub.1-C.sub.6 alkyl glycidyl ethers,
bisphenol-A diglycidyl ether and glycidyl esters of C.sub.1-C.sub.6
carboxylic acids. Other suitable epoxy-group containing compounds
are epoxidized vegetable oils, such as epoxidized linseed oil (ELO)
or epoxidized soybean oil (ESO). Without wishing to be bound by any
theory it is believed that the epoxy groups in these compounds
react with one or more hydroxyl group in the humins thereby
creating an ether moiety. If such a reaction takes place, the
epoxy-group containing compound also produces an additional
hydroxyl group. Although the ether group formed has a lower
hydrophilicity than the original hydroxyl group the newly formed
hydroxyl group may cause an increase in hydrophilicity of the
resulting product. To counteract the increase in hydrophilicity the
epoxy-group containing compound is suitably a compound with one or
more significantly hydrophobic chains. Such chains may preferably
comprise from 8 to 35 carbon atoms. Vegetable oils provide very
suitable reactive compounds. It is believed that by the reaction of
humins with epoxidized vegetable oils, flexible chains are
introduced onto the humins macromolecule through the aliphatic
segments of the triglycerides-containing oils. As the aliphatic
segments of such oils tend to be rather long, e.g. having 12 to 30
carbon atoms, any hydrophilic effect of a hydroxyl group formed is
offset by the hydrophobic character of the long carbon chain.
[0021] It is preferred that the reactive compound is selected from
carboxylic anhydrides and olefins. Acyl halides tend to produce
hydrogen halides as by-products. Such acidic by-products are
generally undesirable. Carboxylic acids react at a slower rate than
the anhydrides, which makes the use of anhydrides preferable. It
was found that the reaction of an olefin with the furyl rings in
the humins also proceed relatively fast. Therefore, the reactive
compound is preferably a carboxylic anhydride selected from a
C.sub.2-C.sub.6 carboxylic anhydride, in particular from acetic
anhydride and succinic anhydride, or an olefin having from 4 to 8
carbon atoms. In case of such an olefin the olefin is suitably
selected from the group consisting of butenes, pentenes, hexenes,
heptenes, octenes and combinations thereof.
[0022] The amount of the reactive compound may vary within wide
ranges. Typically, the skilled person will ensure that there is at
least a stoichiometric amount of reactive compound vis-a-vis the
amount of functional groups in the humins. Such is, however, not
necessary. If the desired property, e.g. the reduced viscosity, is
obtained by a partial conversion of the functional groups in the
humins the skilled person may be satisfied with a partial
conversion only. The amount of the reactive compound per amount of
humins is suitably from 0.001 to 1.0 g, preferably 0.05 to 0.5 g
reactive compound per g humins. This range is applicable to any of
the reactive compounds described above.
[0023] The humins that can be used in the process of the present
invention have suitably been obtained in the conversion of a
carbohydrate or 5-hydroxymethylfurfural. The structural features of
the humins that are produced by these conversions have been studied
as reported in S. Patil et al., Energy Fuels, 2012, 26, 5281-5291.
The study concludes that the structures as shown by their IR
spectra are quite similar except for some peaks that are attributed
to a carbonyl group. These minor differences in humins do not lead
away from the conclusion that all humins contain hydroxyl,
carboxylic, carbonyl and furan groups. Preferably, the humins have
been obtained from the conversion of fructose or glucose. The
conversion has suitably been conducted in the presence of an acid
catalyst. The humins have preferably been produced by the
conversion of fructose and/or glucose in the presence of water, an
alcohol or a carboxylic acid at a temperature in the range of 105
to 250.degree. C. For more details for such conversion reference is
made to WO 2007/104514 and WO 2007/104515. It has further been
found that it may be advantageous to increase the number of
hydroxyl groups in the humins. Such may be the case when the humins
contain a large number of carbonyl groups. In such instances the
humins are preferably subjected to a reduction reaction. In such a
reduction reaction at least a portion of the carbonyl groups in the
humins are reduced to hydroxyl groups. To achieve the reduction the
humins may be subjected to hydrogenation, preferably over a
metal-containing catalyst. The metal may be selected from the
groups 8 to 10 of the Periodic Table of the Elements, such as
nickel, cobalt, optionally comprising tungsten and/or molybdenum as
additive. Alternatively, the metal-containing catalyst may comprise
a metal of the platinum group of metals, such as platinum,
ruthenium, palladium or rhodium. When the hydrogenation is carried
out under rather severe conditions a variety of reductions may take
place, including the hydrogenation of the furan rings in the
humins. In order to prevent this from happening, the reduction of
carbonyl groups may preferably be carried out by means of one or
more metal hydrides. Suitable catalysts include the metal hydrides
NaBH.sub.4, NaAlH.sub.4, LiAlH.sub.4, LiBH.sub.4,
Zn(BH.sub.4).sub.2 and Ca(BH.sub.4).sub.2. When the humins comprise
a sufficiently high number of hydroxyl groups no pre-treatment with
hydrogen or a metal hydride is needed.
[0024] The process according to the present invention is conducted
in the presence of an organic aprotic solvent. It has been found
that the presence of a solvent mitigates the tendency of the humins
to form a solid cellular structure. It is further believed that due
to the solvent the accessibility of the reactive compound to the
desired functional groups in the humins is improved, thereby
facilitating the reaction between the functional group and the
reactive compound. The organic aprotic solvents may be selected
from a wide range of compounds. These solvents may consist of
compounds comprising only carbon and hydrogen atoms or may also
contain one or more heteroatoms, such as one or more oxygen or
nitrogen atoms. As the humins comprise several polar groups, such
as hydroxyl, carboxyl and carbonyl and furyl groups, the organic
solvent is suitably also polar. On the other hand, the modified
humins tend to have an increased amount of apolar groups and
especially when hydroxyl groups of the humins have been allowed to
react with the reactive compound, they have a reduced content of
polar hydroxyl groups. Therefore, the organic solvent is
aprotic.
[0025] The organic aprotic solvent suitably comprises a heteroatom,
in particular an oxygen atom. It is therefore feasible to use an
ether as organic solvent. However, the use of ethers is not
preferred as the majority of ethers have a low polarity so that the
dissolution of humins in the ether is very limited. The organic
solvent is preferably selected from the group consisting of
aldehydes, ketones, carboxylic acid esters and combinations
thereof. Although it is feasible to use alcohols, such as
C.sub.2-C.sub.6 alcohols as solvent, the use of alcohols is not
envisaged. The drawback of these solvents reside in that they may
react with a number of reactive compounds, such as carboxylic
acids, carboxylic anhydrides and epoxy-containing compounds. They
may thus react with the reactive compound used. Therefore, the
organic aprotic solvent is suitably different from an alcohol, and
preferably does not comprise an alcohol. Suitable organic solvents
include aldehyde solvents, ketone solvents, amide solvents or ester
solvents. The ester group in ester solvents may also be an internal
ester group such as in a lactone. Such organic solvents may
comprise from 1 to 8 carbon atoms. Thus, preferably, the organic
aprotic solvent comprises one or more oxygen atoms, suitably being
not in a hydroxyl group, and 1 to 8 carbon atoms. Suitable examples
of these organic aprotic solvents are formaldehyde, acetaldehyde,
acetone, methyl ethyl ketone, methyl iso-butyl ketone, dimethyl
formamide, diethyl formamide, acetamide, gamma-valerolactone, ethyl
formate, propyl formate, methyl acetate, ethyl acetate, methyl
levulinate, ethyl levulinate, and mixtures of two or more of these
compounds. More preferably, the organic aprotic solvent is selected
from the group consisting of aldehydes, ketones, carboxylic esters
and combinations thereof. Therefore the solvent is suitably
selected from the group consisting of acetone, methyl ethyl ketone,
methyl iso-butyl ketone, gamma-valerolactone, ethyl formate, propyl
formate, methyl acetate, ethyl acetate, methyl levulinate, ethyl
levulinate, and combinations thereof.
[0026] Also the use of carboxylic acid esters, such as
C.sub.1-C.sub.4-alkyl esters of C.sub.1-C.sub.4 carboxylic acids,
e.g. methyl formate, ethyl acetate, as organic solvent is feasible.
When an ester is used as organic aprotic solvent the ester solvent
may undergo transesterification, which involves a saponification
reaction of the ester solvent followed by an esterification
reaction of the carboxylic acid that results from the
saponification, with a hydroxyl group in the humins macromolecule.
Although these reactions are generally performed in the presence of
a dedicated catalyst to enhance the reaction rate they also proceed
without the use of a catalyst. Hence, when an ester is used as
solvent some transesterification reactions may occur, albeit at a
low reaction rate. It is expected that the carboxylic acid formed
from the ester reacts with the humins macromolecule. Hence, the
carboxylic acid component of the ester may be retrieved as acyl
moiety in the modified humins. This is generally not a problem, as
the proportion will be low in view of the slow reactions, and,
further, the conversion of the hydroxyl group of the humins
macromolecule into an ester group has an advantageous effect on the
hydrophobicity of the modified humins.
[0027] Therefore, aldehydes, ketones and their combinations are
especially preferred. Suitable aldehydes and ketones have 2 to 12
carbon atoms. These compounds tend to be liquid and their boiling
points in many instances are such that reflux conditions may be
applied which provide the desired temperature for the conversion.
Suitable aldehydes include acetaldehyde, propanal, butanal,
pentanal and mixtures thereof. Suitable ketones include acetone,
methyl ethyl ketone, methyl isobutyl ketone, diethyl ketone, and
combinations thereof.
[0028] The skilled person will understand that the humins before
the contact with the reactive compound may not completely dissolve
in the organic aprotic solvent used. However, the modified humins
will at least partly dissolve in the organic solvent.
[0029] The amount of aprotic solvent may vary within wide ranges.
The skilled person will seek a balance between a sufficient volume
of solvent and dissolution of humins to achieve a good
accessibility of the reactive compound to the functional groups in
the humins on the one hand, and a satisfactorily small amount of
solvent to reduce the required heat input for achieving the desired
conversion and also to avoid unnecessary effort for the separation
of the organic solvent from the modified humins on the other hand.
Suitably the amount of organic aprotic solvent is in the range of 1
to 50 mL, preferably from 2 to 20 mL, more preferably from 5 to 10
mL organic aprotic solvent per gram humins.
[0030] When the humins and the reactive compound have been brought
into contact a humins-containing admixture is obtained. This
admixture is then maintained at elevated temperature to achieve the
reaction between the reactive compound and the humins, in
particular the reaction with functional groups in the humins. The
temperature may be selected such that the organic solvent and the
reactive compounds are liquid. Evidently, it is preferable that the
reaction pressure is atmospheric so that no pressure vessel is
required to carry out the conversion. The reaction temperature
suitably is in the range of 50 to 250.degree. C., preferably in the
range of 50 to 180.degree. C., more preferably in the range of 60
to 100.degree. C. At temperatures above 180.degree. C., and at a
significant rate above 250.degree. C., humins macromolecules are
subjected to auto-crosslinking reactions, and the humins may even
start to degrade and start forming solid cellular carbonaceous
products. At temperatures below 50.degree. C. the reaction of the
reactive compound with the humins takes place very slowly. In order
to avoid any risk of auto-crosslinking and degradation of the
modified humins the contact of the humins-containing admixture is
preferably above 50.degree. C. and below 150.degree. C., e.g. at
most 145.degree. C.
[0031] Although atmospheric pressure is preferred, elevated
pressures are also feasible. Therefore, the reaction pressure is
preferably in the range of 1 to 15 bar. If the pressure is below 1
bar the organic solvent may start boiling at an undesirably low
temperature. If the pressure is above 15 bar unnecessary costs and
effort are to be incurred without any significant advantage. The
humins-containing admixture is suitably maintained at the elevated
temperature for a period in the range of 0.2 to 6 h. When the
temperature is selected at the lower part of the preferred range,
the reaction time may be prolonged. Alternatively, if the reaction
temperature is at the higher end of the range, the reaction time
may be shortened. This is the more so when the conversion does not
need to be complete, and when a partial conversion of the humins is
already satisfactory.
[0032] The modified humins are recovered after the conversion of
the humins-containing admixture. The recovery of the modified
humins can take place in a variety of well-known methods. Such
methods include liquid-liquid separation by phase separation of the
modified humins from the organic solvent. Such may be accomplished
by adding an anti-solvent to the conversion product. An example
would be to add water or an aqueous medium to the conversion
product. This method has as drawback that the organic solvent and
the anti-solvent are obtained as a mixture. If the solvent is to be
re-used in the process, a separation of the solvent from the
anti-solvent is then required. An advantage of adding water or
another aqueous medium resides in that any organic salts that are
present in the humins may be dissolved in the aqueous medium. A
very convenient way to recover the modified humins is by
evaporation of the organic aprotic solvent. Especially when the
organic solvent has a relatively low boiling point, this manner is
advantageous.
[0033] As indicated above, the modified humins that are obtained
show an increased hydrophobicity, compared with the humins that
were used as starting material. The recovered modified humins are
therefore more easily treated with aqueous media. It is relatively
easy to subject the modified humins to a washing treatment to
remove any remaining water-soluble components that are left in the
modified humins. The modified humins may thus suitably be washed
with an aqueous washing liquid. The aqueous washing liquid is
suitably water. However, if it is expected that acidic components
are left in the modified humins the aqueous washing liquid may be
alkaline to facilitate the removal of these acidic components. The
pH of the washing liquid may then be in the range of 7 to 12.
Alternatively, if basic components are left in the modified humins,
the washing liquid may suitably be acidic, e.g. having a pH of 2 to
7. The washing treatment may be conducted on the modified humins
per se. It is also possible to wash a solution of the modified
humins in a water-immiscible solvent. If the organic aprotic
solvent that has been used for forming the humins-containing
admixture is not miscible with water, this may be used for washing
the modified humins formed, after which the modified humins are
recovered. However, such a treatment has the disadvantage that any
non-reacted reactive component may also be taken up in the aqueous
washing liquid with the risk that such reactive compound is
difficult to recover. Preferably, the modified humins are taken up
in a water-immiscible solvent and the solution obtained is then
subjected to liquid-liquid extraction with the aqueous washing
liquid. After separation of the aqueous phase from the solvent
phase the solvent may be separated from the modified humins, e g.
by evaporation, so that purified modified humins are obtained.
[0034] The modified humins obtainable by the process according to
the present invention are advantageous products. The modified
humins are less hydrophilic, so that they become more suitable as
versatile fuels. That is because the modified humins according to
the present invention suitably have a complex viscosity of at most
50 Pas at 60.degree. C. at a frequency of 10 Hz, as determined in
accordance with ASTM D7175 using an Anton Paar MCR 102 rheometer.
Preferably, the complex viscosity, thus determined, is at most 45
Pas, more preferably at most 40 Pas. Typically the complex
viscosity at 60.degree. C. and determined at 10 Hz, in accordance
with ASTM D7175, is at least 5 Pas. Hence, the complex viscosity of
the modified humins is suitably in the range of 5 to 50 Pas,
preferably from 5 to 40 Pas. The property renders the modified
humins suitable as liquid fuel, e.g. as a residual fuel as defined
in ASTM D396. Such use is similar to the use of mixtures of humins
with an organic oxygenated solvent as described in
WO2016/130005.
[0035] However, the modified humins are not only suitable as fuel
or fuel component. The modified humins may also be used in foundry
applications as foundry resin. In a shell molding process for the
production of sand molds for the casting of metals a mixture of
sand and a thermosetting foundry resin is deposited against a
heated pattern such that the resin cures to form a rigid shell mold
or core section for use in the casting of metals. Similar to
lignin-containing foundry resins as disclosed in U.S. Pat. No.
5,786,409, it has been found that the sodium content of
humins-containing foundry resins, has a detrimental effect on the
quality of the sand cores and sand molds, prepared with humins as
foundry resin. The modified humins according to the present
invention can easily be washed with water or any other aqueous
medium to remove sodium salts, such as sodium chloride, and other
inorganic salt components. Accordingly, any of the modified humins
according to the present invention suitably comprises at most 1000
ppmw, preferably from 10 to 1000 ppmw, more preferably from 50 to
700 ppmw sodium, based on the weight of the modified humins. Due to
the low sodium content the modified humins can be used for several
purposes, including as liquid fuel and foundry resin.
[0036] The modified humins can also be used to impregnate wood,
fabric, paper. The application of the modified humins in the
impregnation of wood has the beneficial aspect that the modified
humins provide an environmentally-friendly protective layer.
Different from painted or treated wood, which is considered
chemical waste, wood that is impregnated with modified humins is
environmentally safe and can be composted or recycled.
[0037] Modified humins according to some embodiments of the present
invention are characterized by the fact that they comprise furyl
groups and that they further comprise acyl moieties derived from a
reactive compound selected from the group consisting of a
carboxylic acid, an acyl halide, and a carboxylic anhydride. The
modified humins may further comprise other moieties such as
levulinate and/or carbohydrate moieties. The furyl moieties may be
present in the form of furfuryl or methylfurfuryl groups. The
modified humins according to this embodiment contain ester groups.
These ester groups may be attached to the furyl rings or to
methylfuryl groups. Alternatively, ester groups may be linked to a
carbohydrate moiety and may be the result of a reaction between a
hydroxyl group of the carbohydrate moiety with a carboxylic acid or
anhydride, an acyl chloride or a carboxylic acid ester. Suitably
the acyl moieties are the residues of carboxylic acids having a
number of carbon atoms in the range of 1 to 25 carbon atoms.
Preferably the acyl moieties are selected from formyl, acetyl,
propionyl, butyryl groups and combinations thereof. Acetyl groups
are particularly preferred as modified humins having such acyl
groups show an excellent solubility in various organic solvents and
also show an excellent viscosity behavior.
[0038] Modified humins also show a surprising property. They are
electrically conductive. This property may render them suitable for
use in applications wherein other electrically conductive polymers
may be used. It has further been found that when the modified
humins are subjected to a heat treatment, i.e. an exposure to heat
of about 200 to 500.degree. C., solidification of the modified
humins occur which have an increased electrical conductivity.
[0039] It has surprisingly been found that modified humins that
comprise furyl groups and further comprise acyl moieties that are
residues of succinic acid show a particularly increased
conductivity. When humins are contacted with succinic anhydride at
elevated temperature, a viscous product is obtained. At increasing
temperature the viscosity of the resulting product is also
enhanced. The modified humins that are thus obtained already show
an interesting electric conductivity. It has been shown that when
the recovered modified humins are subjected to the above-mentioned
heat treatment, e.g. when they are further heated to a temperature
above 250.degree. C. up to 450.degree. C., the modified humins
further react and a shiny grey solid product is obtained which
shows enhanced electrically conductive properties after such
carbonization. Modified humins in general and succinate-modified
humins in particular are therefore suitable for applications
wherein also other conductive polymers can be used, such as in
organic solar cells, printing electronic circuits, organic
light-emitting diodes, actuators, electrodes, in particular
sacrificial electrodes, electrochromism, supercapacitors, chemical
sensors and biosensors, flexible transparent displays,
electromagnetic shielding and for microwave-absorbent coatings. It
would seem that they may be very useful for application as dyes in
solar cells. The effect is very sustainable and does not appear to
deteriorate over time. It appears that the succinate-modified
humins absorb radiation in the visible area, as shown by UV
spectroscopy analysis. The modified humins may be grafted on a
substrate, e.g. titanium dioxide, before or after the heat
treatment. When the modified humins are grafted on a substrate,
e.g., TiO.sub.2, the grafted material may be subjected to a further
heat treatment at e.g. a temperature of up to 450.degree. C.
Alternatively, the modified humins may be subjected to such heat
treatment and the solid product obtained may be grafted onto the
substrate. In view of their properties the materials obtained could
be used in dye-sensitized solar cells. Therefore the invention also
relates to the use of humins that comprise acyl moieties that are
residues of succinic acid as photosensitizer in dye-sensitized
solar cells.
[0040] The modified humins comprise succinyl moieties in addition
to the furyl moieties. Each residue of succinic acid may be linked
to one or two chains in the humins. When the modified humins has
been subjected to a further heat treatment to obtain a solid
conductive material, a product is obtained wherein succinic acid
residues have reacted with two hydroxyl groups, creating a
condensed product. Without wishing to be bound by any theory, it is
believed that during the heat treatment also radical formation
takes place that result in internal rearrangement of the humins
macromolecules. Thereby polycyclic aromatic rings and combinations
of conjugated bonds are formed in the macromolecules, which may
provide the electric conductivity observed.
[0041] In another embodiment of the present invention the modified
humins comprise furyl groups and in addition further comprise
phenyl or oxa-[2,2,1]-bicycloheptenyl groups derived from a
reactive compound. These modified humins are the result of a Diels
Alder reaction from the furan rings in the humins with a dienophile
provided by an olefin as reactive compound. The contact between the
furan rings and the olefinic double bond leads to a Diels Alder
reaction, similar to the reaction described in e.g. WO 2013/048248.
It is known that a furan ring and a dienophile may react to an
oxa-[2,2,1]-bicycloheptene compound. The bicyclic ether obtained
may be dehydrated with concurrent dehydrogenation to form a phenyl
ring. Although such a dehydration reaction may be catalyzed via the
use of a specific catalyst, the reaction may also proceed without
the use of a catalyst. The modified humins according to the present
invention may therefore comprise phenyl groups or
oxa-bicycloheptenyl groups. Dependent on the chain length of the
olefin used as reactive compound, the modified humins comprise a
phenyl or oxa-bicycloheptenyl group comprising a substituent. The
reaction makes it also possible to obtain aromatic compounds from
such modified humins. To obtain the aromatic compounds the modified
humins macromolecules are decomposed e.g. by exposure to acids or
bases, in particular strong acidic or strong alkali solutions. The
olefin that is preferably used as reactive compound in the
derivatization of humins suitably comprises from 4 to 20 carbon
atoms, preferably from 4 to 8 carbon atoms. The substituent or
substituents on the resulting phenyl or oxa-bicycloheptenyl group
may thus suitably have a total number of carbon atoms of 2 to 18,
preferably of 2 to 6. Especially when the olefin is a hydrocarbon
the resulting modified humins have a good solubility in apolar
organic solvents such as toluene. This renders these modified
humins excellently suitable for use as liquid fuel. In a further
embodiment the modified humins comprise, in addition to furyl
groups, also ether moieties derived from a reactive compound
selected from epoxy-group containing compounds. The epoxy group
reacts with hydroxyl groups in the humins thereby binding the rest
of the epoxy-group containing compound to the humins chains,
thereby forming an ether bond. When the epoxy-group containing
compound comprises a hydrophobic moiety, the resulting modified
humins may thus also obtain a higher hydrophobicity. That will
facilitate the removal of any water-soluble component from the
humins. Moreover, the modified humins are better suitable as fuel
or for any other purpose. The epoxy-group containing compound that
may be used as reactive compound is suitably selected from the
group consisting of C.sub.1-C.sub.6 alkyl glycidyl ethers,
bisphenol A diglycidyl ethers, glycidyl esters of C.sub.1-C.sub.6
carboxylic acids, epoxidized vegetable oils and combinations
thereof. If an epoxidized vegetable oil is used, the oil is
suitably epoxidized sunflower oil or epoxidized linseed oil.
[0042] The invention will be further illustrated by means of the
following examples.
Example 1
[0043] Humins obtained from the dehydration of fructose with
methanol in the presence of sulfuric acid by means of a method
described in WO 2007/104514, were used in a number of experiments.
The humins contained some sodium and sulfur residues from the
dehydration reaction and neutralization with sodium hydroxide.
[0044] A round-bottom flask equipped with a reflux condenser and
mechanical stirrer was charged with a quantity of these humins and
a quantity of ethyl acetate (boiling point 77.1.degree. C.) in an
amount of 2.5 ml ethyl acetate per gram humins. Under mechanical
stirring the mixture was heated to a reflux temperature to obtain a
homogeneous dispersion. Then acetic anhydride was added in a ratio
to the humins as indicated in Table 1, the temperature was
maintained at reflux temperature (about 80.degree. C.), and the
reaction was continued for 3 h.
[0045] The reaction mixture showed that the product obtained was
soluble in ethyl acetate. The reaction mixture was washed with
water, creating two liquid phases which were separated in a
separation funnel. The wash treatment was done three times. The
organic phase was evaporated yielding the modified humins.
[0046] The solubility of the modified humins was tested in a
variety of solvents at 90.degree. C. When less than 1 mg/ml of the
modified humins dissolved in the solvent at 90.degree. C., it was
considered insoluble.
[0047] The modified humins appeared to be insoluble in water,
toluene. They were soluble in acetone, ethyl acetate and
tetrahydrofuran.
[0048] Some of the modified humins were subjected to elemental
analysis to determine the amount of sodium and sulfur in the
modified humins. For comparison reasons also the original amount of
Na and S in the starting humins was determined.
[0049] The results are shown in Table 1. Table 1 shows the
Experiment No., the amount of acetic anhydride added, based on the
amount of starting humins (expressed as AcA, g/g), the amounts of
sodium and sulfur of the starting humins (expressed as Na.sub.0 and
S.sub.0, in % wt), the amounts of sodium and sulfur in the modified
humins (expressed as Na.sub.m and S.sub.m, in % wt), the
.eta..sub.0 and the .eta..sub.m, expressed in Pas.
TABLE-US-00001 TABLE 1 Ex. No. AcA, g/g Na.sub.0, % wt S.sub.0, %
wt Na.sub.m, % wt S.sub.m, % wt 1 0.22 1.4 0.2 0.035 0.004 2 0.12
1.4 0.2 0.034 0.004
[0050] Some other experiments were conducted in the same way as
experiments 1 and 2, with the exception that the weight ratio of
acetic anhydride to humins was varied; the weight ratios used were
0.31 g/g, 0.43 g/g and 0.53 g/g. The other reaction conditions were
the same. The results were similar to those obtained in experiment
Nos. 1 and 2.
Example 2
[0051] Experiment No. 2 was repeated with three different humins.
The humins were all obtained in the dehydration of sugars, in one
instance the sugars consisted of 93% wt fructose and 7% wt glucose
(experiment No. 3), and in two instances the sugars consisted of
fructose only (experiment Nos. 4 and 5). The procedure as described
for Experiment No. 2 was repeated in all of Experiment Nos. 3 to
5.
[0052] The complex viscosity at 60, 80, 100 and 120.degree. C. at
an angular frequency from 6.28 to 628 rad/s (1-100 Hz) was
determined in accordance with ASTM D7175 using an Anton Paar MCR
102 rheometer. The measurements were made for the starting humins
(.eta..sub.0) and the modified humins obtained (.eta..sub.m).
[0053] The results are shown in Table 2. Table 2 shows the
Experiment No., the amount of acetic anhydride added, based on the
amount of starting humins (expressed as AcA, g/g), the .eta..sub.0
and the .eta..sub.m, expressed in Pas, and determined at 60.degree.
C. at 10 Hz and 100 Hz.
TABLE-US-00002 TABLE 2 .eta..sub.0, Pa s, .eta..sub.0, Pa s,
.eta..sub.m, Pa s, .eta..sub.m, Pa s, Exp. No. AcA, g/g 10 Hz 100
Hz 10 Hz 100 Hz 3 0.22 68.6 73.6 8.2 10.6 4 0.22 254 264 34.9 36.6
5 0.22 41.5 55.9 11.8 15.7
[0054] The results show that when different humins are taken as
starting material the viscosities of the modified humins are
considerably reduced, compared to those of the starting humins.
Comparative Example 1
[0055] The humins that were used in Example 1 were contacted with
water in an attempt to remove sodium and sulfur. A two-phase
mixture of transparent water and black humins was mixed with a
mechanical stirrer at room temperature to obtain a black dispersion
of humins in water. The dispersion was left to settle. However,
after two days a mixture was obtained comprising an aqueous phase
that was black, an intermediate phase comprising a dispersion of
humins and water and a humins phase comprising a significant
proportion of water. This experiment showed that separation of the
humins from the water was not practical. Washing humins to
selectively remove inorganic salts, such as sodium and sulfur salt
components appeared unsuccessful.
Example 3
[0056] A round-bottom flask equipped with a reflux condenser and
mechanical stirrer was charged with 25 g of humins and 20 mL
acetone. Under stirring the mixture was heated to reflux to obtain
a dispersion of humins in acetone (boiling point 56.degree. C.). A
quantity of 0.25 mL of valeric anhydride (about 0.24 g) was added
and the reaction was continued under reflux (about 60.degree. C.)
for 4 h. Subsequently, the acetone was evaporated and the modified
humins obtained were a viscous fluid, soluble in acetone and
insoluble in water.
Example 4
[0057] A round-bottom flask equipped with a reflux condenser and
mechanical stirrer was charged with 10 g of humins and 10 mL
acetone. Under stirring the mixture was heated to reflux
temperature to obtain a dispersion of humins in acetone. A quantity
of 0.8 g of stearic anhydride was added and the reaction was
continued at under reflux for 3 h. Then the acetone was evaporated
whereafter the final amount of acetone was removed at 30.degree. C.
in a vacuum oven. Modified humins were obtained as a viscous liquid
that was soluble in acetone.
Example 5
[0058] A round-bottom flask equipped with a reflux condenser and
mechanical stirrer was charged with 25 g of humins and 25 mL of
acetic acid. Acetic acid was used as both solvent and reactive
compound. Under stirring the mixture was heated to reflux and the
reaction was then continued under reflux for 4 h. The acetic acid
was removed via evaporation under reduced pressure and subsequently
by drying the modified humins in a vacuum oven at 40.degree. C.
overnight. Modified humins were recovered as a viscous liquid,
soluble in acetone, but insoluble in water or toluene.
Example 6
[0059] A round-bottom flask equipped with a reflux condenser and
mechanical stirrer was charged with 11 g of humins and 10 mL of
acetone. Under stirring the mixture was heated to reflux
temperature to obtain a dispersion of humins in acetone. A quantity
of 1 g of sebacic acid was added. The reaction mixture was heated
to reflux in about 1 h and the reaction was continued under reflux
for 3 h. Then the acetone was removed by evaporation, whereafter
the final amount of acetone was removed at 30.degree. C. in a
vacuum oven. Modified humins were obtained as a viscous liquid that
was soluble in acetone.
Example 7
[0060] A round-bottom flask equipped with a reflux condenser and
mechanical stirrer was charged with 10 g of humins and 10 mL of
acetone. Under stirring the mixture was heated to obtain a
dispersion of humins in acetone. A quantity of 0.1 g of stearoyl
chloride was added. The reaction mixture was further heated to
reflux and the reaction was continued under reflux for 3 h. Then
the acetone was removed by evaporation. Modified humins were
obtained as a viscous liquid that was soluble in acetone.
Example 8
[0061] The dipropylene glycol ester of maleic anhydride was
prepared by reacting dipropylene glycol and maleic anhydride in a
molar ratio of 1:2 under nitrogen at 100.degree. C. for 3 h. The
obtained product was a yellow liquid.
[0062] A round-bottom flask equipped with a reflux condenser and
mechanical stirrer was charged with 10 g of humins and 5 mL of
isopropanol (boiling point 82.6.degree. C.). Under stirring the
mixture was heated to reflux temperature to obtain a dispersion of
humins. Then 5 g of dipropylene glycol maleate ester as described
hereinabove was added, and the reaction was conducted at reflux
temperature for 3 h. Isopropanol was evaporated and the modified
humins obtained were recovered as viscous liquid. The product is
soluble in alcohols, acetone and ethyl acetate.
Comparative Example 2
[0063] A round-bottom flask equipped with a reflux condenser and
mechanical stirrer was charged with 22 g of humins and 1 mL of
water. Under stirring the mixture was heated to its boiling point
to obtain a colloidal mixture of humins. Then a quantity of 2.5 g
of a 20% wt solution of maleic anhydride in water was added. The
reaction mixture was heated to maintain reflux for about 1 h. The
product precipitated at the end of the reaction. The water was
removed by phase separation. Modified humins were obtained as a
massive solid material. This material was insoluble in any of the
solvents above, indicating that the product has been subject to
auto-crosslinking in the presence of maleic acid.
Example 9
[0064] A round-bottom flask equipped with a reflux condenser and
mechanical stirrer was charged with 18 g of humins and 22 mL of
acetone. Under stirring the mixture was heated to obtain a
dispersion of humins in acetone. A quantity of 1.8 g of epoxidized
linseed oil was added. The reaction mixture was further heated to
reflux and the reaction was continued at reflux for 3 h. Modified
humins were obtained as a viscous product that was dissolved in
acetone. Then the acetone was removed by evaporation.
[0065] When the product obtained was put in an oven at 150.degree.
C. for 2 h, the material appeared to start crosslinking and a final
solid product was obtained that was insoluble in any of the
solvents mentioned above.
Example 10
[0066] A round-bottom flask equipped with a reflux condenser and
mechanical stirrer was charged with 20 g of humins and 20 mL of
ethyl acetate. The mixture was stirred at reflux temperature to
obtain a dispersion of humins in ethyl acetate. A quantity of 10 mL
of 1-hexene (6.7 g) was added and the reaction was allowed to
proceed at reflux temperature (about 80.degree. C.) for up to 4
hours. The solution was allowed to cool to ambient temperature. The
modified humins obtained appeared soluble in ethyl acetate.
[0067] An additional amount of 20 mL of ethyl acetate was added.
The obtained mixture was introduced into a separation funnel and
was washed three times with water. The organic phase was subjected
to evaporation to remove the ethyl acetate, yielding a viscous
product.
Example 11
[0068] A round-bottom flask equipped with a reflux condenser and
mechanical stirrer was charged with 22 g of humins and 7 mL of
acetone. Under stirring the mixture was heated to reflux
temperature to obtain a dispersion of humins in acetone. A quantity
of 2.12 g of succinic anhydride was added and the reaction was
continued for 3 h whilst maintaining reflux conditions. Then the
acetone was evaporated wherein the final amount of acetone was
removed at 30.degree. C. in a vacuum oven. Modified humins were
obtained as a viscous liquid that was soluble in acetone. It was
tested and showed photosensitizer activity in dye-sensitized solar
cells (DSSC).
Example 12
[0069] A round-bottom flask equipped with a reflux condenser and
mechanical stirrer was charged with 22 g of humins and 20 mL of
acetone. Under stirring the mixture was heated to reflux
temperature to obtain a dispersion of humins in acetone. A quantity
of 0.25 g of succinic acid was added and the reaction was continued
at reflux temperature for 3 h. Then the acetone was evaporated
wherein the final amount of acetone was removed at 30.degree. C. in
a vacuum oven. Modified humins were obtained as a viscous product
that was soluble in acetone.
Example 13
[0070] The modified humins obtained in Example 10 were introduced
into an oven that was kept at 450.degree. C., and the modified
humins were exposed to this temperature for 2 min. A solid light
structure was obtained.
[0071] When a voltammogram was determined for this solid structure
it was found that a current was found as a function of the
potential, indicating that the material is conductive.
[0072] This is contrary to e.g. hydrothermally synthesized carbon,
which does not provide a current as a function of potential.
Example 14
[0073] Two humins compositions A and B, having been obtained from
sugar with methanol in the presence of sulfuric acid by means of a
method described in WO 2007/104514, were used in a number of
experiments. Composition A has been obtained from the dehydration
of fructose and composition B has been obtained from the
dehydration of a mixture of fructose and glucose. The humins
compositions contained some sodium and sulfur residues from the
dehydration reaction and neutralization with sodium hydroxide. In
addition, the humin compositions contained some compounds that were
produced in the dehydration reactions. Such compounds included
hydroxymethyl furfural (HMF), methoxymethyl furfural (MMF),
acetoxymethyl furfural (AMF) and glycosides.
[0074] To carry out an acetylation reaction, a round-bottom flask
equipped with a reflux condenser and mechanical stirrer was charged
with a quantity of the humin composition (960 for composition A and
955 g for composition B) and a quantity of ethyl acetate in a ratio
of 2.5 mL of ethyl acetate per gram of humins composition. Under
mechanical stirring the resulting mixture was heated to reflux.
After apparent dissolution 200 mL of acetic acid anhydride was
added in a ratio to the humins as indicated in Table 3, the
temperature was maintained at reflux temperature, and the reaction
was continued for 2.5 h. The still warm reaction mixture was washed
with water and subsequently with a saturated NaCl and
Na.sub.2SO.sub.4 solution. Finally, the remaining organic solvent
was removed was removed at 40.degree. C. in a vacuum oven. The
acetylated humins were analyzed for residual compounds as well as
sodium and sulfur. It appeared that the acetylation reaction
renders the humins compositions water-insoluble whereby the
compounds can be more easily separated.
[0075] Table 3 shows the composition of the starting humins
compositions used. The compositions show the relative amounts of
HMF, MMF, AMF and glycosides (expressed as weight percent based on
the humins composition), as well as the elemental analysis,
expressed as weight percent based on the humins composition).
[0076] After the acetylation reaction the same properties were
again analyzed. Humins composition A resulted in modified humins
composition A' and humins composition B resulted in modified humins
composition B'. The results thereof are shown in Table 4.
TABLE-US-00003 TABLE 3 Component Humins composition A Humins
composition B Feed Fructose Fructose/glucose 93/7 w/w HMF, % wt
11.8 11.0 MMF, % wt 2.3 2.0 AMF, % wt 0.01 0.01 Glycosides, % wt
1.8 25.2 C, % wt 57.9 53.6 H, % wt 5.3 5.9 O, % wt 35.6 40.2 Na, %
wt 0.41 0.33 S, % wt 0.29 0.20
TABLE-US-00004 TABLE 4 Modified humins Modified humins Component
composition A' composition B' HMF, % wt 5.2 5.0 MMF, % wt 2.4 3.2
AMF, % wt 5.9 7.6 Glycosides, % wt 0.2 0.0 C, % wt 58.3 59.9 H, %
wt 5.2 5.1 O, % wt 34.9 35.1 Na, ppmw 569 312 S, ppmw <50
<50
[0077] For these four compositions the rheological properties were
determined in accordance with ASTM D7175 using an Anton Paar MCR
102 rheometer. The complex viscosities (.eta..sub.0 for the
starting humins composition and (.eta..sub.m) for the modified
humins composition obtained) are expressed in Pas, and determined
at 60.degree. C. at 10 and 100 Hz, are shown in Table 5.
TABLE-US-00005 TABLE 5 Comp. A, Comp. B, Comp. A', Comp. B',
.eta..sub.0, Pa s .eta..sub.0, Pa s .eta..sub.m. Pa S .eta..sub.m.
Pa S 10 100 10 100 10 100 10 100 Hz Hz Hz Hz Hz Hz Hz Hz 254 342
68.6 73.6 16.8 21.9 16.7 22.3
* * * * *